The process of gravel packing to restrict and control the passage of particulate materials from a subterranean formation well which penetrates the formation to facilitate the recovery of hydrocarbons is well known. This sand-control method is used to prevent the production of formation sand. In gravel pack operations, a steel screen is typically placed in the wellbore and the surrounding annulus is packed with prepared gravel of a specific size designed to prevent the passage of formation sand. The primary objective is to stabilize the formation while causing minimal impairment to well productivity.
However, horizontal wells present a special, often problematic case for gravel packing and few horizontal wells have been completed in unconsolidated formations. Most operators have completed their horizontal wells in consolidated formations using slotted liners to provide borehole stability and a limited amount of sand control. Pre-packed screens have been successfully used in open-hole horizontal well completions in a friable sandstone. Gravel packing, the industry's more conventional sand control method for vertical and deviated wells, has been applied in horizontal wells.
Previous work showed that low-viscosity carrier fluids such as water could completely pack short horizontal model wells, but there are potential draw-backs for field applications. They may require the use of low gravel concentrations, longer placement times, and larger carrier fluid volumes. In permeable formations, excessive fluid loss can occur, damaging the formation. Gravel settling in the tubing during pumping is another concern.
It would thus be desirable to discover a method which could provide a method for gravel packing generally horizontal wells in permeable formations using conventional gravel concentrations, conventional placement times and lower carrier fluid volumes, while minimizing fluid loss and formation damage.